It is known in the prior art to provide an air-supported or "hover" apparatus. Generally, such devices include a substantially-enclosed housing and means for generating air pressure within the housing to provide an air cushion to float the housing over a support surface. Examples of such devices are shown in U.S. Pat. Nos. 3,170,276, 3,293,836 and 4,245,455, and U.K. Patent Specification No. 1,534,021.
While air-floated devices of the prior art have significant advantages over conventional wheeled products, such devices have certain inherent problems which have yet to be overcome. In particular, such devices typically include an outer housing having a narrow peripheral edge, bezel or seal. During operation, air blown toward the ground by the air pressure means tends to escape from the housing between the ground and the narrow edge structure, which substantially reduces the lifting force on the housing. The rapid escape of air along the periphery of the mower housing also stirs up dust and debris when mowing around shrubbery and the like, which makes mowing difficult and hazardous. Also, because the air is blown downward to keep the housing afloat, the air pressure depresses the grass, causing the cutting blade to leave an uneven cut. Other problems include the inability to maintain lateral or side-to-side stability of the device.
Another disadvantage of prior art air-cushioned mowers is their inability to discharge grass cuttings, which leaves a windrow of cuttings that must be raked up after mowing. Conventional lawn mowers tend to vacuum up grass by the rotary action of the cutting blade. In prior art air-cushioned mowers, however, downwardly blown air pressure used to cream the lifting force by ground effect is not sufficient to effectively discharge grass cuttings. In other words, prior art air-cushioned mowers have not been able to maintain adequate flotation while simultaneously discharging grass clippings from a port.
It is known in the prior art to provide a hover-type apparatus in which air is recycled by the suction side of the impeller used to float the housing. One such system is shown in FIG. 5 of U.S. Pat. No. 4,738,086 to Dunn. A similar teaching is shown in FIG. 2 of U.S. Pat. No. 4,316,001 to Almond, et al. While such systems have some advantages, they do not solve the above-identified problems. Moreover, these systems teach only recycling of air; the clippings themselves are not recycled.
It would therefore be desirable to provide an improved air-floated apparatus that over comes these and other problems associated with the prior art.